E.C. AschenauerBNL Science Council, July 20101

eRHIC - LDRDs  LDRDs on eRHIC Machine Design:  :EIC Polarized Electron Gun; Ilan Ben-Zvi  :Development of a Laser System for Driving the Photocathode of the Polarized Electron Source for the EIC; Triveni Rao  :Simulation, Design, and Prototyping of an FEL, for Proof-of- Principle of Coherent Electron Cooling; Vladimir Litvinenko Details will be presented soon in a talk by V.Litvinenko Details will be presented soon in a talk by V.Litvinenko  LDRDs on eRHIC Physics Case:  Realization of an e+A Physics Event Generator for eRHIC; Thomas Ullrich  Exploring Signatures of Saturation and Universality in e+A Collisions at eRHIC; Raju Venugopalan  Electroweak Physics with an Electron Ion Collider; Bill Marciano  LDRD on eRHIC Detector R&D (hopefully successful this year)  CMOS-Pixel Vertex Detector for eRHIC; Elke-Caroline Aschenauer E.C. Aschenauer BNL Science Council, July 20102

eRHIC Scope e-e-e-e- e+e+e+e+ p Unpolarized and polarized leptons 4-20 (30) GeV Polarized light ions (He 3 ) 215 GeV/u Light ions (d,Si,Cu) Heavy ions (Au,U) (130) GeV/u Polarized protons (325) GeV Electron accelerator RHIC 70% e - beam polarization goal polarized positrons? Center mass energy range: √s= GeV; L~ xHera longitudinal and transverse polarisation for p/He-3 possible e-e-e-e- Mission: Studying the Physics of Strong Color Fields E.C. Aschenauer BNL Science Council, July 20103

RHIC NSRL LINAC Booster AGS Tandems STAR 6:00 o’clock PHENIX 8:00 o’clock (PHOBOS) 10:00 o’clock Jet/C-Polarimeters 12:00 o’clock RF 4:00 o’clock (BRAHMS) 2:00 o’clock From RHIC to eRHIC EBIS ERL Test Facility e e eRHIC eRHIC-Detector & Polarimeters 12:00 o’clock E.C. Aschenauer 4BNL Science Council, July 2010

eSTAR ePHENIX 100m | | Coherente-cooler 22.5 GeV 17.5GeV 12.5 GeV 7.5 GeV Common vacuum chamber 27.5 GeV 2.5 GeV Beam-dump Polarized e-gun eRHIC detector 25 GeV 20 GeV 15 GeV 10 GeV Common vacuum chamber 30 GeV 5 GeV 0.1 GeV RHIC: 325 GeV p or 130 GeV/u Au eRHIC: staging all-in tunnel Gap 5 mm total 0.3 T for 30 GeV SRF linac Vertically separated recirculating passes. # of passes will be chosen to optimize eRHIC cost energy of electron beam is increasing from 5 GeV to 30 GeV by building-up the linac s From RHIC to eRHIC E.C. Aschenauer BNL Science Council, July 20105

Quantum Chromo-Dynamics (QCD) E.C. Aschenauer BNL Science Council, July  Theory of strong (nuclear) interactions  Three colour charges: red, green and blue  Exchange particles (gluons) carry colour charge and can self- interact  Flux is confined: V(r) ~ r, F(r) ~ constant q qq qg √α√α α s = strong coupling constant ≈ 0.3 long range force ~ r gluons can self-interact - more vertices are allowed ~1/r at short range

Features of Quantum Chromo-Dynamics E.C. Aschenauer BNL Science Council, July  Confinement  At large distances, the effective coupling between quarks is large, resulting in confinement (V(r) ~ r)  Free quarks are not observed in nature  Asymptotic freedom  At short distances, the effective coupling between quarks decreases logarithmically  Under such conditions, partons appear to be quasi-free 0.2 fm 0.02 fm fm

QED vs QCD E.C. Aschenauer BNL Science Council, July  Potentials:  long range aspect of V s (r) leads to quark confinement and the existence of nucleons QED QCDQCD Chargeselectric (2)colour (3) gauge bosonsγg (8) charged?noyesyes coupling strength α em = e 2 /4π ≈ 1/137 α s ≈ 0.3

BNL Science Council, July 2010 Measure Glue through DIS 9 Measure of resolution power Measure of inelasticity Measure of momentum fraction of struck quark E.C. Aschenauer Kinematics: Quark splits into gluon splits into quarks … Gluon splits into quarks higher √s increases resolution m m

leptons, quarks and gluons through matter E.C. Aschenauer BNL Science Council, July Effect proportional to velocity and Z/A of material Effect proportional to density  and Z/A of material

Measure Glue through DIS E.C. Aschenauer 11 small x large x Observation of large scaling violations BNL Science Council, July 2010 Strong increase of sea quarks towards Strong increase of sea quarks towards low x low x Density increases with Q 2 Density increases with Q 2 more partons by magnified view more partons by magnified view quark density Dynamic creation of partons at low x gluon density valence quarks x=1 x=10 -5 Gluon density dominates

Bremsstrahlung ~  s ln(1/x) x = P parton /P nucleon small x small x Recombination ~  s  Parton Saturation  s ~1  s << 1  at small x linear evolution gives strongly rising g(x) strongly rising g(x)  violation of Froissart unitary bound  BK/JIMWLK non-linear evolution includes recombination effects  saturation recombination effects  saturation  Dynamically generated scale Saturation Scale: Q 2 s (x) Saturation Scale: Q 2 s (x)  Increases with energy or decreasing x  Scale with Q 2 /Q 2 s (x) instead of x and Q 2 separately 12BNL Science Council, July 2010 Saturation must set in at forward rapidity/low x when gluons start to overlap and when recombination becomes important Solving the BK/JIMWLK equations and making concrete prediction, what are the signatures of saturation and what is the saturation scale are the major objectives of LDRD Start: Fall 2010; PostDoc hired

eRHIC - Reaching the Saturation Regime 13 Saturation:  dAu: Strong hints from RHIC at x ~  p: No (?) hints at Hera up to x=6.32  10 -5, Q 2 = 1-5 GeV 2 Kowalski, Lappi and Venugopalan, PRL 100, (2008) ) ; Armesto et al., PRL 94:022002; Kowalski, Teaney, PRD 68:114005) Nuclear Enhancement: Hera Coverage:  Need lever arm in Q 2 at fixed x to constrain models  Need Q > Q s to study onset of saturation  ep: even 1 TeV is on the low side  eA: √ s = 50 GeV is marginal, around √ s = 100 GeV desirable  20 GeV x 100 GeV  20 GeV x 100 GeV E.C. Aschenauer BNL Science Council, July 2010

Measurements & Techniques  Gluon Distribution G(x,Q 2 )  Scaling violation in F2: δF 2 /δlnQ 2 day 1 measurements (inclusive DIS)  F L ~ xG(x,Q 2 ) requires running at wide range of √s  2+1 jet rates sensitive dominantly to large x  Diffractive vector meson production ([xG(x,Q 2 )] 2 ) ([xG(x,Q 2 )] 2 ) most sensitive method  Space-Time Distribution  Exclusive diffractive VM production (J/) at Q 2 ~0 (photoproduction) Gluonic form factor of nuclei E.C. Aschenauer BNL Science Council, July Writing a MC-program, which simulates all this different processes and incorporates, what was learned about nuclei at RHIC. is the objective of LDRD Especially challenging is the simulation of the nuclei and its break-up. Project started: ep simulation based on saturation model finished. PostDoc started in May will implement nuclear part

F 2 : for Nuclei 15 E.C. Aschenauer BNL Science Council, July 2010 Assumptions:  10GeV x 100GeV/n  √s=63GeV  Ldt = 4/A fb -1  equiv to cm -2 s -1  T=2weeks; DC:50%  Detector: 100% efficient  Q 2 up to kin. limit sx  Statistical errors only  Note: L~1/A antishadowing “sweet” spot R=1 shadowing LHC  =0 RHIC  =3

The Standard Model E.C. Aschenauer BNL Science Council, July

Electromagnetic vs. Weak Interactions E.C. Aschenauer BNL Science Council, July

Access to physics beyond the STD-Model  Measure single spin asymmetries A PV via scattered lepton  Asymmetries in the order of x Q 2 – x Q 2  demanding measurement  impact on detector design and Luminosity  the running of sin 2  w is a basic sin 2  w is a basic feature of EW-theory feature of EW-theory deviation: sign deviation: sign of new physics of new physics E.C. Aschenauer BNL Science Council, July Scale-dependence of Weak Mixing Scale-dependence of Weak Mixing JLab Future JLab Future SLAC Moller SLAC Moller Z 0 pole tension Z 0 pole tension The objective of LDRD is to study the corrections to the A PV asymmetries from radiative corrections. In addition the it will be evaluated if EW physics can b used to study the spin structure of the proton and lepton number violations. The luminosity and detector requirements will be determined. Start: Fall 2010; PostDoc specialized on EW hired

A typical High Energy Detector E.C. Aschenauer BNL Science Council, July Particle types:  neutrinos (missing energy)  muons    hadrons  p  quarks, gluons  jets  electrons, photons,  0  charged particles beam pipe Rough Classification  track detectors for charged particles  “massless” detectors  gas detectors  solid state detectors  magnet coil (solenoid, field || beam axis) Calorimeter for energy measurement  electromagnetic  high Z material (Pb-glas)  absorber (mostly Fe)  flux return yoke + active material active material  hadronic  heavy medium (Fe, Cu, U) + active material + active material

First ideas for a detector concept E.C. Aschenauer Colorado University, March Dipol3TmFED // ZDCDipol3TmFPD //  Dipoles needed to have good forward momentum resolution  Solenoid no magnetic r ~ 0  DIRC, RICH hadron identification  , K, p  high-threshold Cerenkov  fast trigger for scattered lepton  small radiation length extremely critical  low lepton energies, as low as 500MeV  precise vertex reconstruction  separate Beauty (300  m) and Charmed Meson (120  m)

CMOS-Pixel Vertex Detector for eRHIC  Silicon Detectors at Atlas (61 m 2 ) and CMS (198 m 2 )  CMS: huge radiation length  impossible to use for eRHIC electrons do bremsstrahlung  Pixel Detector for eRHIC  Radiation length 0.05%  Pixel-layer-thickness: 50  m not  readout electronics integrated in Pixel  current “chip” sizes 1x2cm 2 to small for forward / backward disks Plan: extend to 5x5cm 2 with 10M pixels with 16  m pitch extend to 5x5cm 2 with 10M pixels with 16  m pitch Vertex resolution ~5  m E.C. Aschenauer BNL Science Council, July Useful for any application, which needs high resolution and low material budget

E.C. Aschenauer BNL Science Council, July and Summary eRHIC many avenues for further many avenues for further important theoretical, important theoretical,experimental and technological developments we have just explored the tip of the iceberg tip of the iceberg to understand gluons you are here  u tot,  d tot L q,g ssss gggg spin sum rule Knowledge about Gluons in p /A Talk by V. Litvinenko

E.C. Aschenauer 23 BACKUP BNL Science Council, July 2010

Nobel Prize, 1943: "for his contribution to the development of the molecular ray method and his discovery of the magnetic moment of the proton"  p = 2.5 nuclear magnetons, ± 10% (1933) Otto Stern Proton spins are used to image the structure and function of the human body using the technique of magnetic resonance imaging. Paul C. Lauterbur Sir Peter Mansfield Nobel Prize, 2003: "for their discoveries concerning magnetic resonance imaging" The Spin of the Proton E.C. Aschenauer DIS - Madrid, April

Important to understand hadron structure: Spin E.C. Aschenauer 25 qqqqqqqq GGGG LgLgLgLg qLqqLqqLqqLq qqqq qqqqqqqq GGGG LgLgLgLg qLqqLqqLqqLq qqqq Is the proton spinning like this? “Helicity sum rule” total u+d+s quark spin angularmomentum gluonspin Where do we go with solving the “spin puzzle” ? N. Bohr W. Pauli BNL Celebration, June 2010 Currently we know: S q z ~ 30% and S g z ~ -8%

 Scaling violations of g 1 (Q 2 -dependence) give indirect access to the gluon distribution via DGLAP evolution. (Q 2 -dependence) give indirect access to the gluon distribution via DGLAP evolution. E.C. Aschenauer 26BNL Science Council, July 2010  RHIC polarized pp collisions at midrapidity directly involve gluons  Rule out large DG for 0.05 < x < 0.2 Δg from inclusive DIS and polarized pp Current knowledge on  g RHIC DIS EIC constrained x-range still limited

x How does it look at EIC 5fb -1 integrated luminosity EIC: Access to ΔG at small x where uncertainties are very large translates into E.C. Aschenauer 27BNL Science Council, July 2010 will constrain

Kretzer KKP   DIS   SIDIS uvuvuvuv uuuu dvdvdvdv dddd ssss gggg                DSSV     What do we know: NLO Fit to World Data BNL Science Council, July  includes all world data from DIS, SIDIS and pp  Kretzer FF favor SU(3) symmetric sea, not so for KKP, DSS   ~25-30% in all cases DSSV: arXiv: Q 2 =10 GeV 2 But how do we access L q and L g in the IMF ??? E.C. Aschenauer

A detector integrated into IR E.C. Aschenauer BNL Science Council, July ZDC FPD  Dipoles needed to have good forward momentum resolution  Solenoid no magnetic r ~ 0  DIRC, RICH hadron identification  , K, p  high-threshold Cerenkov  fast trigger for scattered lepton  radiation length very critical  low lepton energies FED a lot of space for polarimetry and luminosity measurements

EIC - What Luminosity is Needed? 30 syst. uncertainties F L : inclusive measurements at different √ s, assume 1% energy-to-energy normalization assume 1% energy-to-energy normalization Conclusion from this study: good control on systematic uncertainties critical ∫ L dt = 4/A fb -1 (10+100) GeV & 4/A fb -1 (10+50) GeV & 4/A fb -1 (10+50) GeV & 2/A fb -1 (5+50) GeV 2/A fb -1 (5+50) GeV All together 5 weeks at L ~ 1x10 34 cm -2 s -1 & 50% duty cycle (Note: 1000x Hera L) E.C. Aschenauer BNL Science Council, July 2010

Measure the Gluon Form Factor E.C. Aschenauer 31 R A = 1.2A 1/3 fm Elastic scattering on full nucleus  long wavelength gluons (small t) Requirement: Momentum resolution < 10MeV great t resolution Need to detect nuclei break-up products detect e’ in FED BNL Science Council, July 2010 Basic Idea: Studying diffractive exclusive J/  production at Q 2 ~0 Ideal Probe: large photo-production cross section t can be derived from e,e’ and J/  4-momentum

eRHIC – Geometry high-lumi IR 1.6 m m 7 10 mrad 5.4 cm 8.4 cm 10.4 cm 1 m © D.Trbojevic E.C. Aschenauer BNL Science Council, July  Two designs of the IR exist for both low luminosity (~ 3x10 33 ) and high luminosity (~ 2x10 34 ) depends on distance IR to focusing quads  By using a crossing angle (and crab cavities), one can have energy- independent geometries for the IRs and no synchrotron radiation in the detectors  Big advantage in detecting particles at low angle  can go as low as 0.75 o at hadron side  |  | < 5.5 Beam-p: y ~ 6.2 m eRHIC IR1 p /Ae Energy (max), GeV325/13020 Number of bunches16674 nsec Bunch intensity (u), Bunch charge, nC324 Beam current, mA Normalized emittance, 1e-6 m, 95% for p / rms for e Polarization, %7080 rms bunch length, cm β *, cm55 Luminosity, cm -2 s x (including hour-glass effect h=0.851) Luminosity for 30 GeV e-beam operation will be at 20% level

Can we detect DVCS-protons and Au break up p E.C. Aschenauer BNL Science Council, July  track the protons through solenoid, quads and dipole with hector proton track  p=10% proton track  p=20% proton track  p=40% Equivalent to fragmenting protons from Au in Au optics (197/79:1 ~2.5:1) DVCS protons are fine, need more optimization for break-up protons

Questions about QCD  Confinement of color, or why are there no free quarks and gluons at a long distance? a long distance?  What is the internal landscape of the nucleons?  What is the nature of the spin of the nucleon?  What is the three-dimensional spatial landscape of nucleons? Need probes to “see” and “locate” the quarks and gluons, without disturbing them or interfering with their dynamics?  What governs the transition of quarks and gluons into pions and nucleons  What is the role of gluons and gluon self-interactions in nucleons and nuclei?  What is the physics behind the QCD mass scale? BNL Science Council, July 2010  It represents the difference between QED and QCD  Dominates structure of QCD vacuum  Responsible for > 98% of the visible mass in universe The key to the solution The Gluon 34 E.C. Aschenauer

A reminder of Quantum Electro-Dynamics (QED) E.C. Aschenauer BNL Science Council, July  Theory of electromagnetic interactions  Exchange particles (photons) do not carry electric charge  Flux is not confined: V(r) ~ 1/r, F(r) ~ 1/r2 Coupling constant (α): Interaction Strength In QED: α em = 1/137 √α √α Feynman Diagram: e + e - annihilation